This invention relates generally to railroad bridges and more particularly to a system and method for positioning a pile cap underneath an existing elevated bridge assembly to upgrade the bridge assembly to support a rail assembly.
Many existing wooden railroad bridges were built 70 or 80 years ago and are now in the process of being repaired because of deterioration or upgraded to handle the freight loads and speeds of modern trains. Most of the existing wooden railroad bridges are supported by wooden piles topped by wooden pile caps. The repair and upgrade of the bridges includes installing new steel beam piles and topping the new piles with pre-cast, concrete pile caps. Ultimately, the old, wooden piles and caps are removed, and new pre-cast, concrete spans, which are supported by the new caps and piles, are used to support the rail assembly.
A typical concrete pile cap is 17 feet long by three feet wide by three feet deep, and weighs 30,000 pounds. Currently, concrete pile caps are cast with lifting loops at each end so that the pile cap may be lowered straight down from the rail assembly onto the steel piles. This, however, requires that at least portions of all the stingers be removed and that both rails be cut and removed from the rail assembly. Train traffic is interrupted since the rail assembly is separated, and traffic cannot resume until the pile cap is placed on the steel piles and the rail assembly is restored.
It is preferred that upgrading the exiting wooden bridges is done with a minimum interruption of the train traffic. Windows of opportunity for performing the construction are seldom longer than six hours and frequently are as short as forty-five minutes. Current systems and methods in the art do not allow for minimum interruption.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
A system and method for positioning a pile cap underneath an existing bridge assembly is disclosed. A portion of the rail assembly is removed to define an access area. At least three new piles are installed through the access area. The piles include a center pile and two opposing outer piles. Each pile has a proximal end and a distal end. The distal ends of each pile are driven into a support surface so that each pile generally extends from the support surface to the existing elevated rail assembly. The proximal ends of each pile are removed to define a gap between the piles and the existing elevated rail assembly. A new pile cap is then inserted into the gap. To insert the pile cap, a lifting device and a crane are used. The lifting device is used to incrementally insert the pile cap into the gap. The pile cap is supported on the piles and is used to support a new span for supporting the rail assembly.
The foregoing summary is not intended to summarize each potential embodiment, or every aspect of the invention disclosed herein.